This invention relates to a fuel injection type engine and more particularly to an improved injector and method of operating it for an air fuel injected internal combustion engine.
Fuel injection is obtaining considerable recognition, particularly for use in providing good fuel economy and emission control for two cycle engines wherein fuel is injected directly into the combustion chamber of the engine. Frequently the type of fuel injector employed also injects high pressure air along with the fuel for a variety of reasons.
Although this type of injection system has some advantages, it has certain disadvantages, particularly in conjunction with some applications for two cycle engines. Such engines are frequently used with the type of small watercraft where the watercraft may be started and stopped repeatedly. This type of watercraft operation is quite common with those type of small watercraft in which the rider operates the watercraft in a swimming suit and frequently may be displaced from the watercraft due to its sporting nature. With such arrangement, the engine is stopped when the rider becomes displaced and then restarted when the rider returns to the watercraft and desires to continue operation.
The starting and stopping of fuel injected engines, however, present certain problems. When the engine is stopped, some residual fuel may be present in the injector and particularly around the injection nozzle, valve and valve seat associated therewith. This residual fuel will become heated to a high enough temperature to cause ionization even when the engine is not running due to the high residual heat within the combustion chamber. The carbonization of the fuel gives rise to particles which will then adversely affect the operation of the injector.
It is, therefore, a principal object of this invention to provide an improved fuel injection system wherein fuel will be purged from the injection nozzle during the time after the engine is shut off.
It is a further object to this invention to provide an improved air fuel injector system for an engine where the fuel supply is discontinued when the engine is shut down but the air supply is continued for a brief period of time thereafter in order to purge fuel from the injector.